1. Field of the Invention
The present invention relates to image-forming apparatuses such as monochromic/full-color copying machine, printer, facsimile machine and multifunctional processing machine.
2. Description of the Related Art
In an image-forming apparatus in intermediate transfer mode, toner images in various colors formed on a latent image-supporting member are respectively primarily transferred to and superimposed on an intermediate transfer member, and the superimposed image is secondarily transferred collectively onto an image-receiving medium. In such an image-forming apparatus, there remains a small amount of toner on the intermediate transfer member after the secondary transfer.
Formation of a hard release layer on the surface of the intermediate transfer member for improvement of the secondary transfer rate may be effective in improving the toner release characteristics. However, there may be some improvement in secondary transfer efficiency in such an image-forming apparatus, but, during primary transfer of the toner image formed on the latent image-supporting member onto the intermediate transfer member, the toner image is held and pressurized between the latent image-supporting member and the intermediate transfer member, giving other new problems such as aggregation of toner and hollow defects of the resulting image. Specifically, the hard release layer on the intermediate transfer member surface is formed for easier release of the toner, and a part of the toner aggregate formed by pressurization during primary transfer adheres to and remains more on the latent image-supporting member than on the intermediate transfer member higher in release characteristics, thus prohibiting primary transfer. The hollow defects become more distinctive, particularly in the central area of a character or thin line image where the pressure and thus the toner aggregation force are higher.